Newly settled coral larvae may secrete a skeleton, but if conditions
are poor, polyps may "bail out" and re-enter the water column,
presumably with the ability to find a better place to settle. The arrow
points to a polyp in the process of departing.

Sempers larva of a Zoanthellid, probably Palythoa sp., found
on coral reefs (Order Zoanthidea, Phylum Cnidaria, usually colonial and
anemone-like)